Growing cells in nanocellulose

Marianna Salin

Growing bacterial cells and yeast cells produces rye bread, and growing viruses produces vaccines. Growing human cells can produce, for instance, a miniature liver, which can then be used for testing drugs instead of testing on animals.

"The Division of Pharmaceutical Biosciences at the University of Helsinki has already succeeded in growing a preform of a miniature liver. The researchers have used UPM's cellulose-based GrowDex hydrogel as the culture medium," says product head Pia Nilsson from UPM Biochemicals.

Why settle for just a miniature liver? Is it not possible to grow a complete spare organ in a laboratory?

"The matter of how a fresh organ could be grown to replace a damaged one is being researched intensively," says Nilsson.

UPM participates in the research by sending five-millilitre GrowDex samples to research groups around the world, at a constantly increasing pace. In addition to healthy tissues, the researchers also grow cancerous tissues for drug testing. In Finland, a wound care product that uses UPM's nanocellulose is also being developed.

For decades, cells have been grown on flat surfaces in low glass or plastic dishes. However, the most ambitious goals of biomedicine require a three-dimensional space in which the cells and the tissue formed by the cells are able to freely choose the direction in which they grow, as per their nature. An example of this type of space is the microwell plate, which can be used in the same manner as a test tube. At the same time, the importance of the gel surrounding the cells, i.e. the growing medium, increases.

"One of the advantages of GrowDex is that it basically consists of just pure cellulose fibre and water. No gelling agents have been added and it does not contain any animal proteins. In addition, GrowDex resembles the extracellular matrix present in human organs due to the appropriate size of its fibres."

Cellulose works its way from Finnish forests into biomedical laboratories through an ordinary pulp mill.

"We carefully choose an appropriate batch of pulp, which is further processed in Lappeenranta," says Nilsson. She does not reveal the exact details of the process, as they are the ones that set GrowDex apart from other nanocellulose products. The principle, however, is simple. You take cellulose fibres that are a couple of millimetres long and slightly thinner than a human hair. These fibres are ground until they break up into nanofibrils that are thousands of times smaller. At the same time, the uneven pulp mass turns into a smooth gel. Done.